Remove all legacy STM32/Mamba names from source files. Update all imports,
comments, and docstring references across the codebase.
- stm32_protocol.py → esp32_protocol.py (inter-board UART codec)
- mamba_protocol.py → balance_protocol.py (Orin↔ESP32 BALANCE CAN codec)
- Updated: stm32_cmd_node.py, can_bridge_node.py, all test files,
conftest.py, protocol_defs.py, jlink_gimbal.py
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>